Fluorescent probes for the adrenergic receptor site and for the catalytic adenylyl cyclase site will be used to study the system derived from avian erythrocytes and from single heart cells. Enriched membrane preparations will be obtained by discontinuous gradient centrifugation of post-mitochondrial supernatants after cell disruption by nitrogen cavitation. Preparations will be studied for changes in the fluorescence parameters including, fluorescence enhancement, spectral shifts of excitation and emission, changes in lifetime and time-dependent polarization anisotropy. Studies will be performed with a probe in the catalytic site while agonists, antagonists, and/or GTP are used to bind to the receptor and/or regulatory sites. Opposite studies will be performed with a probe in the receptor site. With probes in both sites, energy transfer experiments will be performed. Also, energy transfer experiments will be performed between probes in either the receptor or catalytic site and probes in the membrane. Attempts will be made to utilize the probes to identify the receptor and/or catalytic moieties in two-dimensional PAGE of membrane proteins after detergent solubilization. Lastly, an aim of this project is to obtain enriched fractions of the system by affinity chromatography.